Image display device and motion detection method of image display device

ABSTRACT

Disclosed are an image display device and a method of controlling an image display device. The image display device includes a motion detection unit for detecting a motion of a user and provides a welcome feedback to the user in the form of a visual signal, an audio signal, or both according to whether the motion of the user is detected or not, thereby drawing attention of the user or switching a display state to reduce power consumption of the image display device. The image display device determines a motion exception event that is not regarded a user motion on the basis of an overall change or a local change in pixel value between image frames, thereby preventing the display panel from being activated by a non-human-related factor such as a sudden change in illuminance or a movement of a periodically operating object.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/929,851, filed on Jul. 15, 2020, which claims the benefit of anearlier filing date and right of priority to International ApplicationNo. PCT/KR2019/008988, filed on Jul. 19, 2019, the contents of which areall hereby incorporated by reference herein their entirety.

TECHNICAL FIELD

The present invention relates to an image display device and a method ofcontrolling the image display device. More particularly, the presentinvention relates to an image display device having a motion detectionfunction and to a method of controlling the image display device.

BACKGROUND ART

In general, an image display device displays an image on a displaymodule, such as a cathode ray tube, a liquid crystal panel, anelectroluminescent panel, a light emitting diode panel, a plasma displaypanel, and the like.

Recently, image display devices have become larger and more advanced infunctionality. With this trend, the sizes of display panels of imagedisplay devices have been increased. However, the larger and advanceddisplay devices have a problem in that power consumption increases withthe size of the display panel.

To solve this problem, technology development has been focused onenhancing the performance of a power saving function. However, there isa limit in power saving because the size of the display in a displaydevice is not variable. For this reason, quite recently, an imagedisplay device in which a display size is variable according to settingshas been proposed and has attracted great attention as a next generationimage display device.

On the other hand, there is a conventional power saving technique inwhich an image display device is equipped with a camera module to detecta motion of a user in front of the image display device. The imagedisplay device switches to a power saving mode when there is no usermotion detected. However, the conventional technique has a problem inthat a sudden change in ambient illuminance or a movement of aperiodically moving object is erroneously detected as a motion of auser, resulting in an unexpected activation of the image display device.

DISCLOSURE Technical Problem

An objective of the present invention is to provide an image displaydevice that detects a motion of a user and outputs at least one of light(i.e., visual signal) and sound (i.e., audio signal) as welcomefeedback. Another objective of the present invention is to provide animage display device capable of detecting a motion of a user andswitching a display panel from a partial view state to a zero viewstate. A further objective of the present invention is to provide amotion detection method for an image display device, the method beingcapable of preventing a sudden change in illuminance or a movement of aperiodically moving object which is not a human being from beingrecognized as a motion of a user, thereby preventing erroneous detectionof a user motion, which contributes to power saving.

Technical Solution

In order to solve the above problems, according to one exemplaryembodiment of the present invention, there is provided an image displaydevice equipped with a motion detection unit for detecting a motion of auser. When a user motion is detected by the motion detection unit with adisplay panel being in a zero-view state, a light emitting unit and/oran audio output unit is controlled to output light and/or sound as theirwelcome feedback signal.

In order to solve the above problems, according to one exemplaryembodiment of the present invention, there is provided an image displaydevice equipped with a motion detection unit for detecting a motion of auser. When the motion of a user is not detected by the motion detectionunit for a predetermined period of time while a display panel is in apartial view state, the display panel is switched from the partial viewstate to a zero-view state.

In order to solve the problems occurring in the related art, accordingto one exemplary embodiment of the present invention, there is provideda motion detection method of an image display device. The methodincludes a motion exclusion process of determining whether it is amotion exclusion condition on the basis of an overall change, a localchange, or both in pixel brightness value between two temporallyadjacent frames each being composed of a plurality of blocks, therebypreventing erroneous detection in detecting a motion of a user.

Advantageous Effects

As described above, the image display device according to the presentinvention can draw user's attention by outputting light, sound, or bothas welcome feedback after detecting a user motion. In addition, theimage display device according to the present invention can save powerand maximize space utilization by detecting a motion of a user andswitching a display panel from a partial view state to a zero view statewhen no user motion is detected. In addition, the motion detectionmethod of the image display device according to the present inventioncan prevent erroneous user motion detection by preventing a suddenchange in illuminance or a movement of a periodically moving object frombeing recognized as a user motion.

DESCRIPTION OF DRAWINGS

FIGS. 1 and 2 are schematic views illustrating an image display device100 according to one exemplary embodiment of the present invention.

FIG. 3 is a block diagram of the image display device 100 according toone exemplary embodiment of the present invention.

FIGS. 4 and 5 are schematic views illustrating a welcome feedback modeof the image display device 100 according to one exemplary embodiment ofthe present invention.

FIG. 6 is a view illustrating a control flow when a welcome feedbacksignal is provided according to the results of a motion detection in theimage display device 100 according to one exemplary embodiment of thepresent invention.

FIG. 7 is a view illustrating a control flow when a display panel isswitched from a partial view state to a zero-view state according to theresults of a motion detection in the image display device 100 accordingto one exemplary embodiment of the present invention.

FIG. 8 is a schematic view illustrating a control flow when the displaypanel is switched from the partial view state to the zero-view stateaccording to the results of a motion detection in the image displaydevice 100 according to one exemplary embodiment of the presentinvention.

FIG. 9 is a block diagram of a motion detection unit 160 of the imagedisplay device 100 according to one exemplary embodiment of the presentinvention.

FIG. 10 is a flowchart illustrating a motion detection method of theimage display device 100 according to one exemplary embodiment of thepresent invention.

FIG. 11 is a flowchart illustrating a motion detection method of theimage display device 100 according to one exemplary embodiment of thepresent invention.

BEST MODE

Hereinafter, specific embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

The advantages and features of the present invention and the manner ofachieving them will become apparent with reference to the embodimentsdescribed in detail below and the accompanying drawings. The presentinvention may, however, be embodied in many different forms and shouldnot be construed as being limited to the embodiments set forth herein.Rather, these embodiments are provided so that the present inventionwill be thorough and complete and will fully convey the concept of theinvention to those skilled in the art. Thus, the present invention willbe defined only by the scope of the appended claims. Like numbers referto like elements throughout the following description herein.

FIGS. 1 and 2 are schematic views illustrating an image display device100 according to one exemplary embodiment of the present invention, andFIG. 3 is a block diagram of the image display device 100 according toone exemplary embodiment of the present invention.

Referring to FIGS. 1 to 3 , the image display device 100 according toone exemplary embodiment of the present invention includes a rollabledisplay panel 110, a drive unit 120, a housing 101, a motion detectionunit 160, and a controller 170.

The display panel 110 is a flexible display panel 110 that is variablein size. That is, the display panel 110 may be accommodated in thehousing 101 when it is fully rolled down and may be stretched out of thehousing when rolled up. The display panel 110 is, for example, anorganic light emitting diode (OLED) panel.

The drive unit 120 functions to roll up and roll down the display panel110. The drive unit 120 may include a roller (not shown) around whichthe display panel 110 is to be wound and a motor (not shown) whichrotates the roller.

FIG. 2 illustrates an example in which the size of the display panel 110is changed through operation of the drive unit 120. FIG. 2A illustratesa zero view state in which the display panel 110 is fully rolled down,and FIG. 2B illustrates a partial view state in which the display panel110 is partially rolled up. FIG. 2C illustrates a full view state inwhich the display panel 110 is entirely rolled up such that the entiredisplay panel 110 is fully stretched out of the housing. The imagedisplay device 100 according to the present invention may offer variousfunctionalities according to changes in the size of the display panel110. In FIG. 2 , one partial view state is illustrated. The imagedisplay device 100 may have a plurality of partial view states whichdiffer in the height of the display panel 110 according to how muchdegree the display panel 110 is rolled up.

The housing 101 has an internal space for accommodating the displaypanel 110 when the display panel 110 is rolled down. The drive unit 120,the motion detection unit 160, and the controller 170 may installed inthe internal space of the housing 101. The housing 101 is provided witha slit (not shown) through which the display panel 110 can be rolledinto and rolled out of the housing. The housing 101 may be implementedin any shape and size if the shape and size allow the display panel 110to be received in the housing 101. FIG. 1 illustrates an example inwhich the housing is implemented in the form of a rectangular shape.

The housing 101 is provided with a light emitting unit 130, an audiooutput unit 140 and an image capturing unit 150, each of which may bedisposed on the front surface of the housing 101 or on an arbitraryposition while facing forward.

The light emitting unit 130 is a device for emitting light and may beconfigured with light emitting devices such as light emitting diodes(LEDs). The light emitting unit 130 may be configured such that aplurality of light emitting devices is arranged to form predeterminedpatterns. For example, in FIG. 1 , the light emitting unit 130 isconfigured such that the light emitting devices are linearly arranged.The light emitting unit 130 is one of the output means for providing awelcome feedback signal. The welcome feedback refers to visual feedbackor audio feedback provided to a user when the image display device 100detects a motion of a user while the image display device 100 is in thezero view state. The controller 170, which will be described later, mayprovide visual feedback with various colors or patterns by controllingtoggles or color changes of the light emitting devices of the lightemitting unit 130 when a motion of a user is detected. The lightemitting unit 130 is disposed toward the front side of the housing 101so that a user in front of the image display device 100 can easilyrecognize the welcome feedback. In FIG. 1 , the light emitting unit 130is integrally formed with the front surface of the housing 101. However,the arrangement of the light emitting unit 130 is not limited thereto.That is, the light emitting unit 130 can be disposed at any place if itcan face forward so that a user can easily recognize the welcomefeedback. For example, the light emitting unit 130 can be disposed onthe upper surface or the side surface of the housing 101.

The audio output unit 140 may include a speaker module to output a soundsignal. The audio output unit 140 is one of the output means forproviding the welcome feedback in the form of sound. The controller 170to be described later in detail may perform output an audio signal(i.e., sound) corresponding to welcome feedback to the audio output unit140 when a motion of a user is detected. In this case, the welcomefeedback is provided through the audio output unit 140. In FIG. 1 , theaudio output unit 140 is integrally formed on the front surface of thehousing 101. However, the arrangement of the audio output unit 140 isnot limited thereto. For example, the audio output unit 140 can bedisposed on the upper surface or the side surface of the housing 101 ifsound (i.e., audio signal) can be output toward the front side of theimage display device 100.

The image capturing unit 150 is a device for capturing an image of anobject exterior to the image display device 100. The image capturingunit 150 includes an image sensor such as a CCD or a CMOS. The imagecapturing unit 150 may be disposed on the front surface of the housing101 or disposed to face forward. FIG. 1 illustrates an arrangementexample in which the image capturing unit 150 is fixed to the centerportion of the front surface of the housing 101. The image capturingunit 150 is a means for imaging an object in front of the image displaydevice 100 to detect a motion of a user. Therefore, the image capturingunit 150 can be disposed on the upper surface or the side surface of thehousing 101 instead of the front surface if it can capture an image ofan object existing in front of the image display device 100.

The motion detection unit 160 detects a motion of a user by analyzingtwo temporally adjacent frames (i.e., a temporally front frame and atemporally rear frame) captured by the image capturing unit 150. Themotion detector 160 includes an algorithm to process input frames anddetect a motion of a user and a processor for executing the algorithm.

The controller 170 controls the light emitting unit 130, the audiooutput unit 140, and the drive unit 120 according to the results of amotion detection performed by the motion detector 160. The controller170 includes a control algorithm, a processor for executing the controlalgorithm, and a memory in which the control algorithm is stored.

When the display panel 110 is in the zero view state, the controller 170activates the image capturing unit 150 and the motion detection unit 160to detect whether there is a motion of a user. When a motion of a useris detected by the motion detection unit 160, at least one of the lightemitting unit 130 and the audio output unit 140 is activated to providea welcome feedback in the form of light or sound. As such, when a motionof a user is detected in the zero-view state of the display panel 110,the image display device 100 draw a user's attention by sending awelcome message (i.e., welcome feedback). The above-described welcomefeedback may be provided only when a welcome feedback function is set toON state.

The welcome feedback may be provided in various ways. For example, thecontroller 170 may output various forms of welcome feedback bycontrolling emission colors, brightness, toggles, dimming, etc. of theplurality of light emitting devices of the light emitting unit 130. Inaddition, the controller 170 may have a plurality of welcome feedbacks.The controller 170 may allow the audio output unit 140 to output awelcome feedback in various forms such as music, specific sound, andhuman voice.

In the present embodiment, there are two welcome feedback modes. Forexample, in one welcome feedback mode (first mode), in a case where adevice that is listed in a device connection history record of the imagedisplay device 100 is detected when a user application program such asSmartTinkQ is executed, when a motion of a user is detected, thecontroller 170 performs control such that both a visual feedback and anaudio feedback are provided to the user through the light emitting unit130 and the audio output unit 140, respectively. In the other welcomefeedback mode (second mode), in a case where a device that is listed inthe device connection history record of the image display device 100 isnot detected when a user application program such as SmartTinkQ isexecuted, the controller 170 performs control such that only a visualfeedback is provided to the user through the light emitting unit 130.That is, in the present embodiment, there are two feedback modes: afirst mode in which both an audio feedback and a visual feedback areprovided to the user when the device that has been connected to theimage display device is detected through the user application program;and a second mode in which only a visual feedback is provided to theuser when the device that has been connected to the image display deviceis not detected.

FIGS. 4 and 5 are schematic views illustrating welcome feedback modes ofthe image display device 100 according to one exemplary embodiment ofthe present invention.

FIG. 4 illustrates a case in which only the visual welcome feedback isprovided through the light emitting unit 130. While the image displaydevice 100 is in the zero view state, the light emitting unit 130remains inactive as illustrated in FIG. 4A. However, when a user motionis detected, the light emitting unit 130 is toggled from the left to theright (i.e., activated), thereby providing the visual welcome feedbackas illustrated in FIG. 4B.

FIG. 5 illustrates a case in which both the visual feedback and theaudio feedback are provided through the light emitting unit 130 and theaudio output unit 140. While the image display device 100 is in the zeroview state, the light emitting unit 130 and the audio output unit 140remain inactive. Only when a user motion is detected, the light emittingunit 130 is toggled from the left to the right to provide the visualwelcome feedback and the audio output unit 140 is activated to providethe audio welcome feedback, for example, a bell sound of ‘Tirori’ asshown in FIG. 5B.

When the welcome feedback is provided once, the controller 170 disablesthe image capturing unit 150 and the motion detection unit 160 for apredetermined period of time or prevents another welcome feedback frombeing provided for a predetermined period of time even though a motionof a user is detected within the predetermined period of time. Forexample, when a user motion is detected and a welcome feedback is thusprovided, the image display device 100 disables the welcome feedbackfunction for first 30 seconds such that another welcome feedback cannotbe provided within this period of time regardless of the detection ofanother user motion and then enables the welcome feedback function afterthe first 30 seconds pass. That is, after the first 30 seconds pass,another welcome feedback can be provided according to the results of amotion detection performed by the motion detection unit.

On the other hand, when the display panel 110 is in the partial viewstate, the controller 170 activates the image capturing unit 150 and themotion detection unit 160 to detect whether there is a user motion. Whena user motion is not detected by the motion detection unit 160 for apredetermined period of time, the controller controls the drive unit 120to roll down the display panel 110 so that the display panel 110 isswitched from the partial view state or the full view state to the zeroview state. When the image display device 100 is switched to the zeroview state, the power of the image display device 100 is preferablyturned off. That is, since the controller detects a user motion in thepartial view state of the display panel 110 and switches the displaypanel 110 to the zero view state and turns off the power, it is possibleto reduce power consumption when the image display device 100 is notused.

The image display device 100 according to an exemplary embodiment of thepresent invention may further include the image capturing unit 150 and auser-input interface unit 180.

The image capturing unit 150 receives and processes a broadcast signal,or an image signal output from an external device such as a set-top box,a game console, a computer, and the like. The image capturing unit 150may include a tuner (not illustrated) for processing the broadcastsignal and an external device interface unit (not illustrated) forconnection with an external device. The image signal received by theimage capturing unit 150 is transmitted to the display panel 110 undercontrol of the controller 170 and displayed on the screen of the displaypanel 110.

The user-input interface unit 180 transmits a signal (hereinafter,simply referred to as user input) input by a user to the controller 170or transmits a signal output from the controller 170 to a user. Theuser-input interface unit may include a module for communication with aremote control to receive the user input.

A control method of the image display device 100 according to anexemplary embodiment of the present invention will be described indetail with reference to FIGS. 5 and 6 .

FIG. 6 is a control flow in which a welcome feedback is providedaccording to a motion detection in the image display device 100according to one exemplary embodiment of the present invention.

When a display panel 110 is in a zero-view state (S10), a controller 170checks whether a welcome feedback function is set to ON state (S11).When it is determined that the welcome feedback function is set to ONstate, the controller 170 activates am image capturing unit 150 and amotion detection unit 160 so that a user motion can be detected (S12).

The controller 170 checks whether a device that is listed in aconnection history record in a user application program is detected(S13), and selects one of the welcome feedback modes according to theresults of the checking.

When a user motion is detected (S14) after the device listed in theconnection history record in the user application program is detected(S13), the controller 170 activates an audio output unit 140 and a lightemitting unit 130 so that both of the visual feedback and the audiofeedback can be provided through the light emitting unit 130 and theaudio output unit 140, respectively (S16). In this case, the number oftimes that the welcome feedback is provided may be limited to less thana predetermined value in order to prevent a device operation errorattributable to frequent connections with and disconnections from thedevice from occurring. For example, the welcome feedback mode in whichboth the audio feedback and the visual feedback are provided at the sametime can be performed at most twice a day. After the welcome feedbackmode in which both of the visual feedback and the audio feedback areprovided at the same time is performed twice a day, the controller 170may activate the welcome feedback mode in which only the visual feedbackis provided through the light emitting unit 130 when a user motion isdetected.

On the other hand, when a user motion is detected in a state in whichnone of the devices which are listed in the connection history record inthe user application program is detected (S13), the controller 170activates only the light emitting unit 130 to provide only the visualfeedback (S17).

FIG. 7 is a view illustrating a control flow for a case in which adisplay panel is switched from a partial view state to a zero-view stateaccording to the results of a motion detection in the image displaydevice 100 according to one exemplary embodiment of the presentinvention.

A controller 170 activates an image capturing unit 150 and a motiondetection unit 160 to detect a user motion (S21) in the partial viewstate in which a display panel 110 is partially rolled up (S20). Whenthere is no user motion or no user input through a user-input interfaceunit 180 for a predetermined period of time T₁ (S23), the controllercontrols the display panel 110 to roll the display panel 110 down sothat the display panel 110 is switched to the zero view state from thepartial view state (S24). The predetermined period of time T₁ may varywithin a range of 3 hours to 5 hours. In this case, the controller 170may control the image display device 100 to enter a standby mode (powersaving mode).

On the other hand, when there is no user motion or no user input throughthe user-input interface unit 180 for the predetermined period of timeT₁, the controller 170 may notify the user that the display panel 110 isswitched to the zero view state by displaying a notification messageindicating state switching instead of directly switching the displaypanel 110 to the zero view state. In this case, the user can input a keyinput to interrupt the state transition.

FIG. 8 schematically illustrates a transition from the partial viewstate to the zero view state in the image display device 100 accordingto an exemplary embodiment of the present invention. When there is nouser motion or no user input for the predetermined period of time T₁,the controller 170 performs control such that the notification messageis displayed on the screen of the display panel 110 of the image displaydevice 100 as illustrated in FIG. 8A. After that, when there is no userinput for a predetermined period of time T₂, the controller may performcontrol such that the display panel 110 is switched to the zero viewstate as illustrated in FIG. 8B. Here, the predetermined period of timeT₂ may vary, for example, in a range of 1 minute to 3 minutes.

Hereinafter, the motion detection unit 160 and the motion detectionmethod of the image display device 100 according to exemplaryembodiments of the present invention will be described with reference toFIGS. 9 to 11 .

FIG. 9 is a block diagram of a motion detection unit 160 of the imagedisplay device 100 according to one exemplary embodiment of the presentinvention. Referring to FIG. 9 , the motion detection unit 160 of theimage display device 100 according to one exemplary embodiment of thepresent invention includes a motion determination unit 161 and a motionexception determination unit 162.

The motion determination unit 161 primarily analyzes image framesphotographed by the image capturing unit 150 to detemiine whether thereis a user motion. The motion determination unit 161 may use variousmotion detection techniques, such as histogram analysis, which performsanalysis by accumulating changes for each block between the imageframes.

The motion detemination unit 161 divides each of the input frames into aplurality of blocks, and determines whether there is a user motion onthe basis of a change (i.e., difference) in pixel brightness of eachblock between the image frames that are consecutively input.

For example, when 12 image frames per second are input through the imagecapturing unit 150 and each of the image frames is composed of 160*120pixels, the motion determination unit 161 divides each image frame into32*24 blocks each being composed of 5*5 pixels, and calculates theaverage of the brightness values of the pixels within each block.

For example, assuming that an interest block is defined as a blockdisposed at a certain position in an image frame and a correspondingblock is defined as a block positioned at the same position in anotherimage frame (i.e., the subsequent image frame), when a change in pixelbrightness value (i.e., change in the average of the brightness valuesof the respective pixels) between the interest block and thecorresponding block is equal to or greater than a predeterminedthreshold value Th₁, the motion determination unit 161 determines theinterest block as a motion block. Hereinafter, a block that does notsatisfy the requirements to be the motion block will be referred to as amotionless block. When the number of the motion blocks in an image frameis n or more, the motion determination unit 161 determines that there isa user motion (i.e., user motion has occurred).

According to another exemplary embodiment, when an event in which thechange in the pixel brightness value (i.e., the average of thebrightness values of the pixels) is equal to or greater than thepredetermined threshold value Th₁ occurs consecutively m or more times,it is determined that the block may be determined as a motion block. Forexample, only when there are m or more consecutive image frames amongwhich the change in the pixel brightness value between the blocksdisposed at the same position respectively in the two consecutive imageframes is equal to or greater than the predetermined threshold valueTh₁, the blocks are determined as motion blocks.

Here, the number n and the number m are variable values that can bearbitrary set. The sensitivity of the motion detection can be adjustedaccording to the values of the numbers n and m. The greater the valuesof the numbers n and m, the higher the sensitivity. When the number n isset to be within a range of 1 to 3 and the number m is set to be withina range of 2 to 4, it is confirmed that the performance of the motiondetection is improved.

On the other hand, the predetermined threshold value Th₁ may vary fromblock to block and may be set according to Equation 1.

Th ₁ =A+[A−B]+C  [Equation 1]

In Equation 1, A is the overall average of the pixel brightness valuedifferences each of which is a change in pixel brightness value betweencorresponding blocks in respective two consecutive image frames, B isthe minimum value of the pixel brightness value differences, and Crepresents white or the weight of the brightness of the block.

In Equation 1, the values A and B vary according the brightness value ofeach frame or each block, and the predetermined threshold value Th₁varies from frame to frame or from block to block.

The motion exception determination unit 162 functions to handle a motionexception event. That is, the motion exception determination unit 162determines a sudden change in illuminance or a movement of aperiodically moving object as an exception of motion. The motionexception determination unit 162 determines whether there occurs amotion exception event on the basis of at least one of the overallchange and a local change in the pixel brightness value between twoconsecutive image frames.

The motion exception determination unit 162 includes a first motionexception determination unit 162 a for determining a sudden change inilluminance caused by light from a vehicle or any external device as anexception of motion. The first motion exception determination unit 162 adetermines the case where a change in the average pixel brightness valuebetween two consecutive image frames is equal to or greater than apredetermined threshold value Th₂ as a motion exception event. That is,the case is not determined as an event in which a user motion hasoccurred. That is, when the difference in the average pixel brightnessvalue between two consecutive image frames is greater than or equal tothe predetermined threshold value Th₂, the case is determined to be anevent in which the illuminance has suddenly changed and is thus excludedfrom detection of a user motion.

Here, the predetermined threshold value Th₂ may be set to one value in arange of 1 to 64. As the value of the predetemined threshold value Th₂is increased, the difference value that can be regarded as a motionexception condition attributable to a sudden change in the illuminanceis increased. Therefore, the larger the predetermined threshold valueTh₂, the sensitivity for detection of a motion exception event islowered. The predetermined threshold value Th₂ may be appropriately setwhile considering the influence of the illuminance of the space in theimage display device 100 is installed. When the predetermined thresholdvalue Th₂ is set to a value within a range of 2 to 5, it is confirmedthat it is possible to more easily detect a motion exception eventattributable to a sudden change in the illuminance.

The motion exception determination unit 162 may include a second motionexception determination unit 162 b to determine the case where thechanges in the average pixel brightness value between every twoconsecutive image frames among a plurality of image frames sequentiallyinput are periodic, as an exception of motion (i.e., motion exceptionevent) attributable to periodic movements of an object. The secondmotion exception determination unit 162 b detects movements of aperiodically moving object (for example, a fan, a clock, or a movingaccessory) disposed around the image display device 100 and determinesthe movement as an exception of motion (i.e., motion exception event).

The motion detection unit 160 further includes a register for storingthe results of detection of periodic movements for each of the pluralityof blocks. For example, when an image frame is divided into 32*24blocks, registers corresponding to as many as the number of the blocksare provided.

The second motion exception determination unit 162 b adds a value of pto the pixel brightness value of each of the motion blocks and storesthe sum in a corresponding one of the registers. On the other hand, foreach of the motionless blocks, a value of q is added and then the sum isstored in a corresponding one of the registers. When the value stored ina certain register reaches or exceeds a predetermined threshold valueTh₃, the block corresponding to the register is regarded as a motionlessblock and treated as an exception of motion when detecting a usermotion.

In the case of blocks corresponding to periodic movements, thebrightness values of the blocks in the respective frames showperiodicity. In order to detect the blocks corresponding to periodicmovements, the weight of p and the weight of q are applied to each ofthe blocks determined to be motion blocks and each of the blocksdetermined to be motionless blocks, respectively. The periodic movementis detected on the basis of the cumulative sum of the values for eachblock. On the case of periodic movements, it is often determined thatthere is a motion. Therefore, the value of p is set to be considerablygreater than the value of q to detect the periodic movement. When thevalue of p is set to a value within a range of 9 to 12, the value of qis set to a value within a range of −3 to 0, and the predeterminedthreshold value Th₃ is set to a value within a range of 140 to 160, itwas confirmed that the periodic movement of an object can be detectedwith good precision.

As described above, when the image display device 100 according to thepresent invention detects a user motion, if a change in illuminanceattributable to a movement of an object (not a human) or a vehicle lightbeam is detected, it is not detemined as a user motion but processed asa motion exception event. That is, such as a case is excluded frommotion detection, thereby preventing erroneous motion detection.

FIG. 10 is a flowchart illustrating a motion detection method of theimage display device 100 according to one exemplary embodiment of thepresent invention.

The motion detection unit 160 sequentially receives image framescaptured by an image capturing unit 150 (S40). In this step, 12 imageframes are input per second. The motion detection unit 160 divides eachof the image frames into a plurality of blocks and calculates an averagevalue of brightness values of respective pixels in each of the blocks(S41).

Then, the difference in average pixel brightness value betweencorresponding blocks within respective two consecutive image frames iscalculated (S42). Next, it is determined whether the difference inaverage pixel brightness value between the corresponding blocks withinthe respective two consecutive image frames is equal to or greater thana predetermined threshold value Th₁. When an event in which thedifference is equal to or greater than the predetermined threshold valueTh₁ occurs m or more times (i.e., over m or more consecutive imageframes), the blocks are detemined as motion blocks. Next, it isdetermined whether the number of the motion blocks is n or more (S33).

When the number of the motion blocks is n or more, it is determined thatthere is a motion of a user. When the number of the motion blocks isless than n, it is determined that there is no motion of a user.

When the number of the motion blocks is n or more, the difference in theoverall pixel brightness value between each of the consecutive imageframes is calculated (S34). When the difference in the overall pixelbrightness value between one image frame and the subsequent image frameis equal to or greater than a predetemined threshold value Th₂, thiscase is detemined as an exception of motion and is excluded fromdetection of a user motion (S35). This corresponds to the function ofthe first motion exception processing unit. When the difference in theoverall pixel brightness value between two consecutive image frames isequal to or greater than the predetermined threshold value Th₂, thiscase is determined that there is a sudden change in illumination and isthus excluded from detection of a user motion (i.e., the case isdetermined as a motion exception event).

On the other hand, when the difference in the overall pixel brightnessvalue between two consecutive image frames is less than thepredetermined threshold value Th₂, this case is determined that there isa user motion. In this case, a motion detection signal is output (S36).

FIG. 11 is a flowchart illustrating a motion detection method of theimage display device 100 according to one exemplary embodiment of thepresent invention.

The motion detection unit 160 receives image frames captured by theimage capturing unit 150 (S40), divides each of the image frames into aplurality of blocks, and calculates a pixel brightness value of eachblock (S41). Here, the pixel brightness value of each block means theaverage of the brightness values of all the pixels in each block.

The difference in the pixel brightness value of each block (i.e., theaverage of the brightness values of all the pixels in each block)between each of the consecutive image frames is calculated (S42). Whenthe difference is less than a predetermined threshold value Th₁, theblock is determined to be a motion block. A block that is not a motionblock is referred to as a motionless block for sake of convenientdescription). The predetermined threshold value Th₁ may vary from blockto block or frame to frame. The predetermined threshold value Th₁ may bedetermined according to Equation 1.

The motion detection unit 160 applies different weights to the motionblocks and the motionless blocks, respectively, and the cumulative sumof the pixel brightness values of each block is stored in acorresponding one of the registers. For example, a value of p is addedto the value stored in a register corresponding to a motion block, and avalue of q is added to the value stored in a register corresponding to amotionless block (S44).

When the cumulative sum stored in a resistor corresponding to a certainblock is equal to or greater than a predetermined threshold Th₃, theblock is determined as an exception of motion and is determined to be amotionless block (S45). This process corresponds to the function of thesecond motion exception processing unit described above. When a certainmovement is periodically detected, this movement is regarded as aperiodic motion of an object. In this case, the motion is determined asan exception of motion.

On the other hand, it is determined whether the number of blocks each ofwhich is determined to be a motion block m or more consecutive times isn or more in each frame (S46). When the number is less than n, it isdetermined that there is no motion of a user in a corresponding one ofthe frames.

In Step S46, when it is determined that there is a motion of a user, adifference in overall pixel brightness value (i.e., the average ofbrightness values of all the pixels in one image frame) between theimage frame and the subsequent image frame is calculated (S47). When thedifference in the overall pixel brightness value between the image frameand the subsequent image frame is equal to or greater than apredetermined threshold value Th₂ (S48), it is determined that there isno motion of a user. That is, this case is determined as an exception ofmotion detection. On the contrary, when the difference is less than thepredetermined threshold value Th₂ (S48), it is determined that there isa motion of a user, and a motion detection signal is output (S49).

As described above, according to the present invention, in order toreduce the power consumption of the image display device 100, a motionof a user existing in front of the image display device 100 is detected,and then a welcome feedback is provided to the user or the image displaydevice is switched to the zero view state. In addition, during detectionof a motion of a user, motion exception events in which a change inpixel brightness value attributable to a sudden change in illuminance ora periodic movement of an object is regarded as an exception of motiondetection are determined. This has an advantage of preventing unexpectedactivation of the image display device.

On the other hand, the operation method of the image display device 100according to the present invention may be implemented in the form of acode that is stored in a processor-readable recording medium provided inthe image display device 100. Examples of the processor-readablerecording medium include all kinds of recording devices that can storedata that can be read by a processor. Specific examples of theprocessor-readable recording medium include a ROM, a RAM, a CD-ROM, amagnetic tape, a floppy disk, an optical data storage device, and thelike. The processor-readable recording medium may be implemented in theform of a carrier wave for transmission of a signal over the Internet.The processor-readable recording medium may also be distributed overcomputer systems connected via a network, and the code may be stored andexecuted in the distributed processor-readable recording medium.

Although the exemplary embodiments of the present invention have beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions, and substitutions arepossible, without departing from the scope and spirit of the presentinvention as defined in the appended claims. It is thus well known tothose skilled in the art that the present invention is not limited tothe exemplary embodiments disclosed in the detailed description butrather cover various modifications, additions, substitutions, andequivalents to the exemplary embodiments.

What is claimed is:
 1. An image display device comprising: a rollabledisplay panel; a motor configured to roll up or down the rollabledisplay panel; a housing having an internal space to accommodate therollable display panel; an image sensor configured to capture an image;a motion detector configured to detect motion by analyzing image framescaptured by the image sensor; and a controller configured to control themotor to roll down the rollable display panel for switching the rollabledisplay panel from a partial view state to a zero view state based on adetermination that motion is not detected by the motion detector for apredetermined period of time while the rollable display panel is in thepartial view state, wherein in the zero view state, the rollable displaypanel is rolled down into the housing, and wherein in the partial viewstate, the rollable display panel is partially rolled up.
 2. The imagedisplay device of claim 1, wherein the motion detector further comprisesa motion determinator configured to: divide each of the image framescaptured by the image sensor into a plurality of blocks, determine achange in pixel brightness value of each of the plurality of blocksacross the image frames that are sequentially input, and determinewhether there is a motion based on the determined change in pixelbrightness values; and a motion detection exception determinatorconfigured to determine whether there is a motion exception event thatis not regarded as the motion based on an overall change and a localchange in pixel brightness value between each of the image frames thatare consecutively input.
 3. The image display device of claim 1, furthercomprising: a user-input interface configured to receive a user input,wherein the controller is further configured to control the motor toroll down the rollable display panel for switching the rollable displaypanel from the partial view state to the zero view state based on adetermination that no user input is received via the user-inputinterface for a predetermined period of time while the rollable displaypanel remains in the partial view state.
 4. The image display deviceaccording to claim 3, wherein the controller is further configured to:cause a display of a message on the rollable display panel based on adetermination that motion is not detected by the motion detector or thatuser input is not received by a user interface for a predeterminedperiod of time T1 while the rollable display panel is in the partialview state, wherein the message corresponds to an alert that power forthe image display device will enter the zero view state; and activatethe motor to roll down the rollable display panel to switch the rollabledisplay panel to the zero view state based on a determination thatmotion is not detected by the motion detector or user input is notreceived by the user interface for a predetermined period of time T2. 5.The image display device of claim 2, wherein the motion determinator isconfigured to: determine a difference in pixel brightness value betweencorresponding blocks within respective two consecutive image frames thatare sequentially input; and determine whether the corresponding blocksare motion blocks based on the determined difference in pixel brightnessvalue being equal to or greater than a first predetermined thresholdvalue Th1, wherein the motion is determined based on a number of motionblocks in a certain frame being a threshold value n or more.
 6. Theimage display device of claim 2, wherein the motion determinator isconfigured to: determine a difference in pixel brightness value betweencorresponding blocks within respective two consecutive image frames thatare sequentially input, and determine whether the corresponding blocksare motion blocks based on the determined difference in pixel brightnessvalue being equal to or greater than a first predetermined thresholdvalue Th1 consecutively occurring m or more times, wherein the motion isdetermined based on a number of the motion blocks in a certain framebeing n or more.
 7. The image display device of claim 6, wherein thefirst predetermined threshold value Th1 varies from frame to frame orfrom block to block.
 8. The image display device of claim 6, wherein themotion determinator includes a first motion exception determinator thatdetermines a motion exception event where the difference in the pixelbrightness value is greater than or equal to a second predeterminedthreshold value Th2.
 9. The image display device of claim 6, wherein themotion determinator includes a second motion exception determinator thatdetermines a motion exception event where periodicity is found indifferences in pixel brightness value within respective two consecutiveimage frames.
 10. The image display device according to claim 9, furthercomprising: a number of registers corresponding to a number of theplurality of blocks in one image frame of the plurality of image frames,wherein each register is used to store a result of detection of aperiodic movement in a corresponding one of the plurality of blocks,wherein the second motion exception determinator adds a value of p to apixel value stored in each of the registers corresponding to therespective motion blocks and a value of q to a pixel value stored ineach of the registers corresponding to respective motionless blocks anddetermines whether each block for which a cumulative value stored in acorresponding register is a motionless block based on the cumulativevalue being greater than or equal to a third predetermined thresholdvalue Th3.
 11. A method of controlling an image display device equippedwith a processor, an image sensor that captures an image frame of anobject exterior to the image display device, a rollable display panel,and a motor configured to roll up or down the rollable display panel,the method comprising: receiving the image frame captured by the imagesensor; detecting motion by analyzing image frames captured by the imagesensor controlling the motor to roll down the rollable display panel forswitching the rollable display panel to a zero view state from a partialview state based on a determination that motion is not detected for apredetermined period of time while the rollable display panel is in thepartial view state, wherein in the zero view state, the rollable displaypanel is rolled down into the housing, and wherein in the partial viewstate, the rollable display panel is partially rolled up.
 12. The methodaccording to claim 11, wherein the detecting motion comprises a step of:dividing the image frames into a plurality of blocks and determining apixel brightness value across each of the plurality of blocks,determining a difference in the pixel brightness value between eachblock of the plurality of the blocks in the image frame and acorresponding block of the plurality of the blocks in a subsequent imageframe, determining whether there is a motion based on the determinationthe difference in the pixel brightness value, and determining whetherthere is a motion exception event that is not regarded as the motionbased on an overall change and a local change in pixel brightness valuebetween each of the image frames that are consecutively input.
 13. Themethod according to claim 11, further comprising: determining whether auser input is received via a user-input interface; and controlling themotor to roll down the rollable display panel such that the rollabledisplay panel is switched from the partial view state to the zero viewstate based on a detemination that no user input is received via theuser-input interface for a predetermined period of time while therollable display panel remains in the partial view state.
 14. The methodaccording to claim 13, further comprising: causing a display of amessage on the rollable display panel based on a determination thatmotion is not detected or that user input is not received by the userinterface for a predetermined period of time T1 while the rollabledisplay panel is in the partial view state, wherein the messagecorresponds to an alert that power for the image display device willenter the zero view state; and activating the motor to roll down therollable display panel to switch the rollable display panel to the zeroview state based on a detemination that motion is not detected or userinput is not received by the user interface for a predetermined periodof time T2.
 15. The method according to claim 12, wherein the detectingmotion comprises a step of: determining a difference in pixel brightnessvalue between corresponding blocks within respective two consecutiveimage frames that are sequentially input; and determining whether thecorresponding blocks are motion blocks based on the determineddifference in pixel brightness value being equal to or greater than afirst predetermined threshold value Thl consecutively occurring m ormore times, wherein the motion is determined based on a number of themotion blocks in a certain frame being n or more.
 16. The methodaccording to claim 12, wherein the detecting motion comprises a step of:determining a difference in pixel brightness value between correspondingblocks within respective two consecutive image frames that aresequentially input, and determining whether the corresponding blocks aremotion blocks based on the determined difference in pixel brightnessvalue being equal to or greater than a first predetermined thresholdvalue Th1 consecutively occurring m or more times, wherein the motion isdetermined based on a number of the motion blocks in a certain framebeing n or more.
 17. The method according to claim 16, wherein the firstpredetermined threshold value Th1 varies from frame to frame or fromblock to block.
 18. The method according to claim 16, wherein thedetermining whether there is a motion exception event comprises a stepof: determining a motion exception event where the difference in thepixel brightness value is greater than or equal to a secondpredetermined threshold value Th2.
 19. The method according to claim 16,wherein the determining whether there is a motion exception eventcomprises a step of: determining a motion exception event whereperiodicity is found in differences in pixel brightness value withinrespective two consecutive image frames.
 20. The method according toclaim 19, wherein the image display device comprises a number ofregisters corresponding to a number of the plurality of blocks in oneimage frame of the plurality of image frames, wherein each register isused to store a result of detection of a periodic movement in acorresponding one of the plurality of blocks, and wherein the methodfurther comprising: adding a value of p to a pixel value stored in eachof the registers corresponding to the respective motion blocks and avalue of q to a pixel value stored in each of the registerscorresponding to respective motionless blocks and determines whethereach block for which a cumulative value stored in a correspondingregister is a motionless block based on the cumulative value beinggreater than or equal to a third predetermined threshold value Th3.